// Copyright 2015-2020 Parity Technologies (UK) Ltd.
// This file is part of OpenEthereum.

// OpenEthereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// OpenEthereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.

//! Auto-updates minimal gas price requirement from a price-info source.

use std::time::{Duration, Instant};

use ansi_term::Colour;
use ethereum_types::U256;
use parity_runtime::Executor;
use price_info::{fetch::Client as FetchClient, Client as PriceInfoClient, PriceInfo};

/// Options for the dynamic gas price recalibrator.
#[derive(Debug, PartialEq)]
pub struct GasPriceCalibratorOptions {
    /// Base transaction price to match against.
    pub usd_per_tx: f32,
    /// How frequently we should recalibrate.
    pub recalibration_period: Duration,
}

/// The gas price validator variant for a `GasPricer`.
#[derive(Debug, PartialEq)]
pub struct GasPriceCalibrator {
    options: GasPriceCalibratorOptions,
    next_calibration: Instant,
    price_info: PriceInfoClient,
}

impl GasPriceCalibrator {
    /// Create a new gas price calibrator.
    pub fn new(
        options: GasPriceCalibratorOptions,
        fetch: FetchClient,
        p: Executor,
        api_endpoint: String,
    ) -> GasPriceCalibrator {
        GasPriceCalibrator {
            options: options,
            next_calibration: Instant::now(),
            price_info: PriceInfoClient::new(fetch, p, api_endpoint),
        }
    }

    pub(crate) fn recalibrate<F: FnOnce(U256) + Sync + Send + 'static>(&mut self, set_price: F) {
        trace!(target: "miner", "Recalibrating {:?} versus {:?}", Instant::now(), self.next_calibration);
        if Instant::now() >= self.next_calibration {
            let usd_per_tx = self.options.usd_per_tx;
            trace!(target: "miner", "Getting price info");

            self.price_info.get(move |price: PriceInfo| {
				trace!(target: "miner", "Price info arrived: {:?}", price);
				let usd_per_eth = price.ethusd;
				let wei_per_usd: f32 = 1.0e18 / usd_per_eth;
				let gas_per_tx: f32 = 21000.0;
				let wei_per_gas: f32 = wei_per_usd * usd_per_tx / gas_per_tx;
				info!(target: "miner", "Updated conversion rate to Ξ1 = {} ({} wei/gas)", Colour::White.bold().paint(format!("US${:.2}", usd_per_eth)), Colour::Yellow.bold().paint(format!("{}", wei_per_gas)));
				set_price(U256::from(wei_per_gas as u64));
			});

            self.next_calibration = Instant::now() + self.options.recalibration_period;
        }
    }
}
